The purpose of this project is to understand the behavior of rabbit spermatozoa during their transport through the female reproductive tract. We will approach this using cinemicrography to assess the characteristics of sperm movement in different compartments of the tract at appropriate times after mating. Working with the same sperm populations we will quantify aerobic sperm metabolism using a new polarographic configuration which permits measurement of oxygen uptake in Lambda volumes. Cohorts of fluorescent labelled sperm will be introduced into appropriate regions of the tract at specific times during sperm transport. In observing the fate of these cohorts, we will determine the kinetics of sperm migration and exchange between compartments of the female tract. Observations on sperm transport after natural mating by cryptorchid males and artificial insemination of immotile sperm will clarify the importance of sperm motility for entry into the cervix and passage to the oviducts during rapid sperm transport. By comparing the movement characteristics of sperm which dissociate from the cervical mucosa during in vitro incubation with that of sperm recovered from the cervical lumen, uterus and vagina, we will gain further insight into the mode of sperm passage through the cervix. The control of sperm passage through the tubal isthmus will be investigated by observing the changes in the distribution of tubal sperm after drug-induced paralysis of oviductal contractions. The role of modulation of sperm motility in controlling transtubal sperm migration will be explored by transferring poorly motile isthmic sperm to the uteri of recipient females. The subsequent distribution and movement characteristics of these sperm in the recipients will indicate whether the motility of such sperm can be reactivated, and will provide further information on the role of sperm motility during transport through specific regions of the female tract.